Method and apparatus for controlling temperature of a substrate

ABSTRACT

A pedestal assembly and method for controlling temperature of a substrate during processing is provided. In one embodiment, the pedestal assembly includes an electrostatic chuck coupled to a metallic base. The electrostatic chuck includes at least one chucking electrode and metallic base includes at least two fluidly isolated conduit loops disposed therein. In another embodiment, the pedestal assembly includes a support member that is coupled to a base by a material layer. The material layer has at least two regions having different coefficients of thermal conductivity. In another embodiment, the support member is an electrostatic chuck. In further embodiments, a pedestal assembly has channels formed between the base and support member for providing cooling gas in proximity to the material layer to further control heat transfer between the support member and the base, thereby controlling the temperature profile of a substrate disposed on the support member.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part application of co-pendingU.S. patent application Ser. No. 10/960,874, Oct. 7, 2004, which isincorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention generally relate to semiconductorsubstrate processing systems. More specifically, the invention relatesto a method and apparatus for controlling temperature of a substrate ina semiconductor substrate processing system.

2. Description of the Related Art

In manufacture of integrated circuits, precise control of variousprocess parameters is required for achieving consistent results within asubstrate, as well as the results that are reproducible from substrateto substrate. During processing, changes in the temperature andtemperature gradients across the substrate may be detrimental tomaterial deposition, etch rate, step coverage, feature taper angles, andother parameters of semiconductor devices. As such, generation of thepre-determined pattern of temperature distribution across the substrateis one of critical requirements for achieving high yield.

In some processing applications, a substrate is retained to a substratepedestal by an electrostatic chuck during processing. The electrostaticchuck is coupled to a base of the pedestal by clamps, adhesive orfasteners. The chuck may be provided with an embedded electric heater,as well as be fluidly coupled to a source of backside heat transfer gasfor controlling substrate temperature during processing. However,conventional substrate pedestals have insufficient means for controllingsubstrate temperature distribution across the diameter of the substrate.The inability to control substrate temperature uniformity has an adverseeffect on process uniformity both within a single substrate and betweensubstrates, device yield and overall quality of processed substrates.

Therefore, there is a need in the art for an improved method andapparatus for controlling temperature of a substrate during processingthe substrate in a semiconductor substrate processing apparatus.

SUMMARY OF THE INVENTION

The present invention generally is a method and apparatus forcontrolling temperature of a substrate during processing the substratein a semiconductor substrate processing apparatus. The method andapparatus enhances temperature control across the diameter of asubstrate, and may be utilized in etch, deposition, implant, and thermalprocessing systems, among other applications where the control of thetemperature profile of a workpiece is desirable.

In one embodiment of the invention, a substrate pedestal assembly isprovided that includes an electrostatic chuck coupled to a metallicbase. The electrostatic chuck includes at least one chucking electrodeand metallic base includes at least two fluidly isolated conduit loopsdisposed therein.

In another embodiment, the pedestal assembly includes a support memberthat is coupled to a base by a material layer. The material layer has atleast two regions having different coefficients of thermal conductivity.In another embodiment, the substrate pedestal assembly includes anelectrostatic chuck. In further embodiments, a pedestal assembly haschannels formed between the base and support member for providingcooling gas in proximity to the material layer to further control heattransfer between the support member and the base, thereby controllingthe temperature profile of a substrate disposed on the support member.

The pedestal assembly includes a support member that is coupled to abase using a material layer. The material layer has at least two regionshaving different coefficients of thermal conductivity. In anotherembodiment, the support member is an electrostatic chuck. In furtherembodiments, a pedestal assembly has channels formed between the baseand support member for providing cooling gas in proximity to thematerial layer to further control heat transfer between the supportmember and the base, thereby facilitating control of the temperatureprofile of a substrate disposed on the support member.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1A is a schematic diagram of an exemplary semiconductor substrateprocessing apparatus comprising a substrate pedestal in accordance withone embodiment of the invention;

FIGS. 1B-1C are partial cross-sectional views of embodiments of asubstrate pedestal having gaps formed in different locations in amaterial layer of the substrate pedestal.

FIG. 2 is a schematic cross-sectional view of the substrate pedestaltaken along a line 2-2 of FIG. 1A;

FIG. 3 is a schematic partial cross-sectional view of another embodimentof the invention;

FIG. 4 is a schematic partial cross-sectional view of another embodimentof the invention; and

FIG. 5 is a schematic partial cross-sectional view of yet anotherembodiment of the invention;

FIG. 6 is a flow diagram of one embodiment of a method for controllingtemperature of a substrate disposed on a substrate pedestal;

FIG. 7 is a vertical sectional view of another embodiment of a base of apedestal assembly;

FIG. 8 is a bottom view of the base of FIG. 7;

FIG. 9 is a partial sectional view of the base of FIG. 7;

FIGS. 10A-H are bottom views of a base illustrating differentconfigurations for routing a conduit formed therein;

FIG. 11 is a bottom view of another embodiment of a base of a pedestalassembly; and

FIG. 12 is a partial sectional views of the base of FIG. 11.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is also contemplated that elements and features of oneembodiment may be beneficially incorporated on other embodiments withoutfurther recitation.

DETAILED DESCRIPTION

The present invention generally is a method and apparatus forcontrolling temperature of a substrate during processing. Althoughinvention is illustratively described in a semiconductor substrateprocessing apparatus, such as, e.g., a processing reactor (or module) ofa CENTURA® integrated semiconductor wafer processing system, availablefrom Applied Materials, Inc. of Santa Clara, Calif., the invention maybe utilized in other processing systems, including etch, deposition,implant and thermal processing, or in other application where control ofthe temperature profile of a substrate or other workpiece is desirable.

FIG. 1 depicts a schematic diagram of an exemplary etch reactor 100having one embodiment of a substrate pedestal assembly 116 that mayillustratively be used to practice the invention. The particularembodiment of the etch reactor 100 shown herein is provided forillustrative purposes and should not be used to limit the scope of theinvention.

Etch reactor 100 generally includes a process chamber 110, a gas panel138 and a controller 140. The process chamber 110 includes a conductivebody (wall) 130 and a ceiling 120 that enclose a process volume. Processgasses are provided to the process volume of the chamber 110 from thegas panel 138.

The controller 140 includes a central processing unit (CPU) 144, amemory 142, and support circuits 146. The controller 140 is coupled toand controls components of the etch reactor 100, processes performed inthe chamber 110, as well as may facilitate an optional data exchangewith databases of an integrated circuit fab.

In the depicted embodiment, the ceiling 120 is a substantially flatdielectric member. Other embodiments of the process chamber 110 may haveother types of ceilings, e.g., a dome-shaped ceiling. Above the ceiling120 is disposed an antenna 112 comprising one or more inductive coilelements (two co-axial coil elements 112A and 112B are illustrativelyshown). The antenna 112 is coupled, through a first matching network170, to a radio-frequency (RF) plasma power source 118.

In one embodiment, the substrate pedestal assembly 116 includes asupport member 126, a thermoconductive layer 134, a base 114, a collarring 152, a joint ring 154, a spacer 178, a ground sleeve 164 and amount assembly 162. The mounting assembly 162 couples the base 114 tothe process chamber 110. The base 114 is generally formed from aluminumor other metallic material. In the depicted embodiment, the base 114further comprises at least one optional embedded heater 158 (one heater158 is illustratively shown), at least one optional embedded insert 168(one annular insert 168 is illustratively shown), and a plurality ofoptional conduits 160 fluidly coupled to a source 182 of a heating orcooling liquid. In this embodiment, the base 114 is further thermallyseparated from the ground sleeve 164 using an optional spacer 178.

The conduits 160 and heater 158 may be utilized to control thetemperature of the base 114, thereby heating or cooling the supportmember 126, thereby controlling, in part, the temperature of a substrate150 disposed on the support member 126 during processing.

The insert 168 is formed from a material having a different coefficientof thermal conductivity than the material of the adjacent regions of thebase 114. Typically, the inserts 168 has a smaller coefficient ofthermal conductivity than the base 114. In a further embodiment, theinserts 168 may be formed from a material having an anisotropic (i.e.direction-dependent coefficient of thermal conductivity). The insert 168functions to locally change the rate of heat transfer between thesupport member 126 through the base 114 to the conduits 160 relative tothe rate of heat transfer though neighboring portions of the base 114not having an insert 168 in the heat transfer path. Thus, by controllingthe number, shape, size, position and coefficient of heat transfer ofthe inserts, the temperature profile of the support member 126, and thesubstrate 150 seated thereon, may be controlled. Although the insert 168is depicted in FIG. 1 shaped as an annular ring, the shape of the insert168 may take any number of forms.

The thermoconductive layer 134 is disposed on a chuck supporting surface180 of the base 114 and facilitates thermal coupling (i.e., heatexchange) between the support member 126 and the base 114. In oneexemplary embodiment, the thermoconductive layer 134 is an adhesivelayer that mechanically bonds the support member 126 to membersupporting surface 180. Alternatively (not shown), the substratepedestal assembly 116 may include a hardware (e.g., clamps, screws, andthe like) adapted for fastening the support member 126 to the base 114.Temperature of the support member 126 and the base 114 is monitoredusing a plurality of sensors (not shown), such as, thermocouples and thelike, that are coupled to a temperature monitor 174.

The support member 126 is disposed on the base 114 and is circumscribedby the rings 152, 154. The support member 126 may be fabricated fromaluminum, ceramic or other materials suitable for supporting thesubstrate 150 during processing. In one embodiment, the support member126 is ceramic. The substrate 150 may rest upon the support member 126by gravity, or alternatively be secured thereto by vacuum, electrostaticforce, mechanical clamps and the like. The embodiment depicted in FIG.1, the support member 126 is an electrostatic chuck 188.

The electrostatic chuck 188 is generally formed from ceramic or similardielectric material and comprises at least one clamping electrode 186controlled using a power supply 128. In a further embodiment, theelectrostatic chuck 188 may comprise at least one RF electrode (notshown) coupled, through a second matching network 124, to a power source122 of substrate bias, and may also include at least one embedded heater184 controlled using a power supply 132.

The electrostatic chuck 188 may further comprise a plurality of gaspassages (not shown), such as grooves, that are formed in a substratesupporting surface 176 of the chuck and fluidly coupled to a source 148of a heat transfer (or backside) gas. In operation, the backside gas(e.g., helium (He)) is provided at controlled pressure into the gaspassages to enhance the heat transfer between the electrostatic chuck188 and the substrate 150. Conventionally, at least the substratesupporting surface 176 of the electrostatic chuck is provided with acoating resistant to the chemistries and temperatures used duringprocessing the substrates.

In one embodiment, the support member 126 comprises at least oneembedded insert 166 (one annular insert 166 is illustratively shown)formed from at least one material having a different coefficient ofthermal conductivity than the material(s) of adjacent regions of thesupport member 126. Typically, the inserts 166 are formed from materialshaving a smaller coefficient of thermal conductivity than thematerial(s) of the adjacent regions. In a further embodiment, theinserts 166 may be formed from materials having an anisotropiccoefficient of thermal conductivity. In an alternate embodiment (notshown), at least one insert 166 may be disposed coplanar with thesubstrate supporting surface 176.

As with the inserts 168 of the base 114, the thermal conductivity, aswell as the shape, dimensions, location, and number of inserts 166 inthe support member 126 may be selectively chosen to control the heattransfer through the pedestal assembly 116 to achieve, in operation, apre-determined pattern of the temperature distribution on the substratesupporting surface 176 of the support member 126 and, as such, acrossthe diameter of the substrate 150.

The thermoconductive layer 134 comprises a plurality of material regions(two annular regions 102, 104 and circular region 106 are illustrativelyshown), at least two of which having different coefficients of thermalconductivity. Each region 102, 104, 108 may be formed from at least onematerial having a different coefficient of thermal conductivity than thematerial(s) of adjacent regions of the thermoconductive layer 134. In afurther embodiment, one or more of the materials comprising the regions102, 104, 106 may have an anisotropic coefficient of thermalconductivity. For example, coefficients of thermal conductivity ofmaterials in the layer 134 in the directions orthogonal or parallel tothe member supporting surface 180 may differ from the coefficients in atleast one other direction. The coefficient of thermal conductivitybetween the regions 102, 104, 106 of the layer 134 may be selected topromote laterally different rates of heat transfer between the chuck 126and base 114, thereby controlling the temperature distribution acrossthe diameter of the substrate 150.

In yet further embodiment, gaps 190 (as shown in FIG. 2A) maybe providedbetween at least two adjacent regions of the thermoconductive layer 134.In the layer 134, such gaps 190 may form either gas-filled or vacuumedvolumes having pre-determined form factors. A gap 190 may alternativelybe formed within a region of the layer 134 (as shown in FIG. 1C).

FIG. 2 depicts a schematic cross-sectional view of the substratepedestal taken along a line 2-2 in FIG. 1A. In the depicted embodiment,the thermoconductive layer 134 illustratively comprises the annularregions 102, 104 and the circular region 106. In alternate embodiments,the layer 134 may comprise either more or less than three regions, aswell as regions having different form factors, for example, the regionsmay be arranged as grids, radially oriented shapes, and polar arraysamong others. The regions of the thermoconductive layer 134 may becomposed from materials (e.g., adhesive materials) applied in a form ofa paste that is further developed into a hard adhesive compound, as wellas in a form of an adhesive tape or an adhesive foil. Thermalconductivity of the materials in the thermoconductive layer 134 may beselected in a range from 0.01 to 200 W/mK and, in one exemplaryembodiment, in a range from 0.1 to 10 W/mK. In yet another embodiment,the adjacent regions have a difference in thermal conductivities in therange of about 0.1 to 10 W/mK, and may have a difference in conductivitybetween an inner most and out most regions of the layer 134 of about 0.1to about 10 W/mK. Examples of suitable adhesive materials include, butnot limited to, pastes and tapes comprising acrylic and silicon basedcompounds. The adhesive materials may additionally include at least onethermally conductive ceramic filler, e.g., aluminum oxide (Al₂O₃),aluminum nitride (AlN), and titanium diboride (TiB₂), and the like. Oneexample of an adhesive tape suitable for the conductive layer 134 issold under the tradename THERMATTACH®, available from Chomerics, adivision of Parker Hannifin Corporation, located in Wolburn, Mass.

In the thermoconductive layer 134, the thermal conductivity, as well asthe form factor, dimensions, and a number of regions having thepre-determined coefficients of thermal conductivity may be selectivelychosen to control the heat transfer between the electrostatic chuck 126and the base 114 to achieve, in operation, a pre-determined pattern ofthe temperature distribution on the substrate supporting surface 176 ofthe chuck and, as such, in the substrate 150. To further control theheat transfer through the conductive layer 134 between the base 114 andsupport member 126, one or more channels 108 are provided to flow a heattransfer medium therethrough. The channels 108 are coupled through thebase 114 to a source 150 of heat transfer medium, such as a cooling gas.Some examples of suitable cooling gases include helium and nitrogen,among others. As the cooling gas disposed in the channels 108 is part ofthe heat transfer path between the chuck 126 and base 114, the positionof the channels 108, and the pressure, flow rate, temperature, densityand composition of the heat transfer medium of cooling gas provided,provides enhanced control of the heat transfer profile through thepedestal assembly 116. Moreover, as the density and flow rate of gas inthe channel 108 may be controlled in-situ during processing of substrate150, the temperature control of the substrate 150 may be changed duringprocessing to further enhance processing performance. Although a singlesource 156 of cooling gas is shown, it is contemplated that one or moresources of cooling gas may be coupled to the channels 108 in a mannersuch that the types, pressures and/or flow rate of cooling gases withinindividual channels 108 may be independently controller, therebyfacilitating an even greater level of temperature control.

In the embodiment depicted in FIG. 1A, the channels 108 are depicted asformed in the member supporting surface 180. However, it is contemplatedthat the channels 108 may be formed at least partially in the membersupporting surface 180, at least partially in the bottom surface of thesupport member 126, or at least partially in the thermally conductivelayer 134, along with combinations thereof. In one embodiment, betweenabout 2 to 10 channels 108 are disposed in the pedestal assembly 116 andprovide with the selectivity maintained at a pressure between about 760Torr (atmospheric pressure) to about 10 Torr. For example, at least oneof the channels 108 may be partially or entirely formed in theelectrostatic chuck 126, as illustrated in FIGS. 3-4. More specifically,FIG. 3 depicts a schematic diagram of a portion of the substratepedestal assembly 116 where the channels 108 are formed entirely in theelectrostatic chuck 126. FIG. 4 depicts a schematic diagram of a portionof the substrate pedestal assembly 116 where the channels 108 arepartially formed in the base 114 and, partially, in the electrostaticchuck 126. FIG. 5 depicts a schematic diagram of a portion of thesubstrate pedestal assembly 116 where the channels 108 are formed in thethermoconductive layer 134. Although in FIG. 5 the channels are showndisposed between different regions 102, 104, 106 of the thermoconductivelayer 134, the one or more of the channels may be formed through one ormore of the regions 102, 104, 106.

Returning to FIG. 1A, at least one of the location, shape, dimensions,and number of the channels 108 and inserts 166, 168 as well as thethermal conductivity of the inserts 166, 168 and gas disposed in thechannels 108, may be selectively chosen to control the heat transferbetween the support member 126 to the base 114 to achieve, in operation,a pre-determined pattern of the temperature distribution on thesubstrate supporting surface 176 of the chuck 126 and, as such, controlthe temperature profile of the substrate 150. In further embodiments,the pressure of the cooling gas in at least one channel 108, as well asthe flow of the cooling liquid in at least one conduit 156 may also beselectively controlled to achieve and/or enhance temperature control ofthe substrate. The heat transfer rate may also be controlled byindividually controlling the type of gas, pressure and/or flow ratebetween respective channels 108.

In yet further embodiments, the pre-determined pattern of thetemperature distribution in the substrate 150 may be achieved usingindividual or combinations of the described control means, e.g., thethermoconductive layer 134, the inserts 166, 168, channels 108, conduits160, the pressure of cooling gas in the channels 108, and the flow ofthe cooling liquid in the conduits 160. Furthermore, in the discussedabove embodiments, pre-determined patterns of the temperaturedistribution on the substrate supporting surface 176 and in thesubstrate 150 may additionally be selectively controlled to compensatefor non-uniformity of the heat fluxes originated, during processing thesubstrate 150, by a plasma of the process gas and/or substrate bias.

FIG. 6 depicts a flow diagram of one embodiment of an inventive methodfor controlling temperature of a substrate processed in a semiconductorsubstrate processing apparatus as a process 600. The process 600illustratively includes the processing steps performed upon thesubstrate 150 during processing in the reactor 100 described in theembodiments above. It is contemplated that the process 600 may beperformed in other processing systems.

The process 600 starts at step 601 and proceeds to step 602. At step602, the substrate 150 is transferred to the pedestal assembly 116disposed in the process chamber 110. At step 604, the substrate 150 ispositioned (e.g., using a substrate robot, not shown) on the substratesupporting surface 176 of the electrostatic chuck 188. At step 606, thepower supply 132 engages the electrostatic chuck 188 to clamp thesubstrate 150 to the supporting surface 176 of the chuck 188. At step608, the substrate 150 is processed (e.g., etched) in the processchamber 110 in accordance with a process recipe executed as directed bythe controller 140. During step 608, the substrate pedestal assembly 116facilitates a pre-determined pattern of temperature distribution in thesubstrate 150, utilizing one or more of the temperature controlattributes of the pedestal assembly 116 discussed in reference to FIGS.1-5 above. Optionally, the rate and/or profile of heat transferredthrough the chuck 114 during step 608 may be adjusted in-situ bychanging one or more of the characteristics of the gas present in one ormore of the channels 108. Upon completion of processing, at step 610,the power supply 132 disengages the electrostatic chuck 188 and, assuch, du-chucks the substrate 150 that is further removed from theprocess chamber 110. At step 612, the process 600 ends.

FIGS. 7-9 are a vertical sectional view, bottom view and a partialsectional view of one embodiment of a base 700. It is contemplated thatthe base 700 may be used to advantage with any of the substrate pedestalassemblies described herein. In the embodiment depicted in FIGS. 7-9,the base 700 includes a top surface 702 and a bottom surface 704. Achannel 706 is formed in the bottom surface 704 of the base 700. Thechannel 706 is covered by a cap 708 to form a fluid conduit 710. Theconduit 710 includes an inlet 714 and outlet 716 configured to accept afitting, facilitating attachment to a heat transfer fluid control source182, as shown in FIG. 1.

In the embodiment depicted in FIGS. 7-9, the channel 706 is machinedinto the bottom surface 704 of the base 700. The machining operation isperformed in a manner that leaves one or more fins 712 extending intothe area defined by channel 706. The fin 712 increases the surface areaof the conduit 710 available for heat transfer, thereby enhancing theheat transfer between the fluid flowing in the conduit 710 and the base700.

A cap 708 is disposed in the channel 706 and coupled to the base 700 todefine the conduit 710. In the embodiment depicted in FIGS. 7-9, the cap708 is continuously welded to the base 700 to prevent leakage of thefluid flowing in the conduit 710 under vacuum conditions. It iscontemplated that the cap 708 may be sealingly coupled to the base 700utilizing other leak-tight methods.

FIGS. 10A-H depict bottom views of the base 700 having differentconfigurations for routing the conduit 710. As shown, the conduit 710may be routed to provide a predetermine temperature profile of thesupport assembly, thereby controlling the temperature profile of thesubstrate supported thereon.

FIGS. 11-12 depict bottom and partial sectional views of anotherembodiment of a base 1100 which may be utilized in the substratepedestal assemblies described herein. The base 1100 depicted in FIGS.11-12 generally include at least two separate cooling loops 1102, 1104formed in the base 1100 to define at least two independentlycontrollable temperature zones 1106, 1108. The cooling loops 1102, 1104are generally conduits formed as described above, or by other suitablemethod. In one embodiment, the first cooling loop 1102 is arrangedradially outward of the second cooling loop 1104 such that thetemperature control zones 1106, 1108 are concentric. It is contemplatedthat the loops 1102, 1104 may radially orientated, or have othergeometric configurations. The cooling loops 1102, 1104 may be coupled toa single source of a temperature controlled heat transfer fluid, or asin the embodiment depicted in FIG. 11, each loop 1102, 1104 may berespectively coupled to a separate heat transfer fluid source 1112, 1114so that the temperature in the zones 1106, 1108 may be independentlycontrolled. Optionally, an insert 1110, similar to the insert 168described above, is laterally disposed between the first and secondcooling loops insert 168 to provide enhanced thermal isolation betweenthe zones 1106, 1108. The insert 1110 may extend to the lower surface ofthe base 1100, as shown in FIG. 11, or be embedded in the base 1100, asshown in FIG. 12.

Thus, a substrate support pedestal assembly has been provided thatenables flexible temperature control of a substrate support thereon. Thedifferent features to the substrate support pedestal assembly may beselected to provide multiple zones of temperature control, therebyenabling the temperature profile of the substrate to be controlled.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. A substrate pedestal assembly comprising: an electrostatic chuckhaving at least one chucking electrode; and a metallic base coupled tothe electrostatic chuck and having at least two isolated fluid conduitloops disposed therein.
 2. The substrate pedestal assembly of claim 1further comprising: an insert disposed between the conduit loops andhaving a coefficient of thermal conductivity less than a coefficient ofthermal conductivity of the base.
 3. The substrate pedestal assembly ofclaim 1, wherein the first conduit is substantially defined in an areaof the base radially inward of the second conduit loop.
 4. The substratepedestal assembly of claim 1, wherein the base further comprises: atleast one fin extending into the at least one of the conduits.
 5. Thesubstrate pedestal assembly of claim 1, wherein the base furthercomprises: a channel formed in the base; and a cap sealingly disposed inthe channel to define one of the conduit loops.
 6. The substratepedestal assembly of claim 5, wherein the channel further comprises: atleast one fin extending from at least one of the cap or the base into aspace defined by the channel.
 7. The substrate pedestal assembly ofclaim 5, wherein the cap is continuously welded to the base.
 8. Thesubstrate pedestal assembly of claim 1 further comprising: a firstheater disposed in the electrostatic chuck; and a second heater disposedin the base.
 9. The substrate pedestal assembly of claim 1 furthercomprising: at least one gas channel formed between the electrostaticchuck and the base.
 10. The substrate pedestal assembly of claim 1further comprising: a material having at least two regions of differentthermal conductivity disposed between the electrostatic chuck and thebase.
 11. The substrate pedestal assembly of claim 1, wherein theconduit loops are orientated substantially parallel to a substratesupport surface of the electrostatic chuck.
 12. A substrate pedestalassembly comprising: a ceramic electrostatic chuck; a chucking electrodedisposed in the ceramic electrostatic chuck; a metallic base coupled toa bottom surface of the electrostatic chuck; a heater disposed in atleast one of the electrostatic chuck or the metallic base; a first fluidconduit loop formed in the metallic base; and a second fluid conduitloop formed in the metallic base and laterally spaced inward of thefirst conduit.
 13. The substrate pedestal assembly of claim 12 furthercomprising: an insert having a coefficient of thermal conductivity lessthan the base disposed between the first and second conduit loops. 14.The substrate pedestal assembly of claim 12 further comprising: a secondheater disposed in the metallic base, wherein the first heater isdisposed in the electrostatic chuck.
 15. The substrate pedestal assemblyof claim 12 further comprising: at least one gas channel formed betweenthe electrostatic chuck and the metallic base.
 16. The substratepedestal assembly of claim 12 further comprising: an adhesive materialhaving at least two regions of different thermal conductivity disposedbetween the electrostatic chuck and the base.
 17. The substrate pedestalassembly of claim 12, wherein the first conduit loop has an orientationsubstantially parallel to a support surface of the electrostatic chuck.18. A processing chamber, comprising: a chamber body; a metallic basedisposed in the chamber body: a ceramic electrostatic chuck coupled tothe metallic base; a chucking electrode disposed in the ceramicelectrostatic chuck; a heater disposed in at least one of theelectrostatic chuck or the metallic base; a first fluid conduit loopformed in the metallic base; and a second fluid conduit loop formed inthe metallic base and laterally spaced inward of the first conduit. 19.The substrate pedestal assembly of claim 18 further comprising: aninsert having a coefficient of thermal conductivity less than the basedisposed between the first and second conduit loops.
 20. The substratepedestal assembly of claim 18 further comprising: at least one gaschannel formed between the electrostatic chuck and the metallic base.21. The substrate pedestal assembly of claim 18 further comprising: anadhesive material having at least two regions of different thermalconductivity disposed between the electrostatic chuck and the base. 22.A method for controlling the temperature profile of a substratesupported on a pedestal assembly comprising: chucking a substrate on asubstrate support of a substrate support pedestal assembly; flowing afirst heat transfer fluid to a first conduit loop disposed in a metallicbase of the substrate support pedestal assembly coupled below thesubstrate support; and flowing a second heat transfer fluid to a secondconduit loop disposed in the metallic base.
 23. The method of claim 22,wherein a temperature of the first heat transfer fluid is controlledindependent from a temperature of the first second heat transfer fluid.24. The method of claim 22 further comprising: changing at least one ofpressure, flow rate, density or composition of the first heat transferfluid while processing the substrate.
 25. The method of claim 22 furthercomprising: providing a heat transfer medium to a passage laterallydisposed in the interface between the substrate support and the base.26. The method of claim 22 further comprising: applying power to aresistive heater disposed in at least one of the substrate support orthe base.
 27. The method of claim 22 further comprising: independentlycontrolling resistive heaters disposed in the substrate support and thebase.